Digital Video Recorders (DVRs) are widely installed and used in public places such as schools and banks for the purposes of security and the management of facilities. The DVRs are developed to overcome the technical limitations of a conventional Closed Circuit Television (CCTV) system. That is, in the DVRs, videos captured by cameras are digitized, processed using a digital compression technology and stored in high-capacity Hard Disk Drives (HDDs), so that the problems of the CCTV system, in which recorded videos deteriorate and recording tapes must be periodically replaced, are removed.
Meanwhile, the DVRs are independent systems that do not need compatibility with external systems, but need special functions such as multi-channel division screen construction or time index search, so that the DVRs has generally adopted an independent format of data compression technology. Conventional data compression technologies not only fail to support some functions that needed in the DVRs but also require large additional overhead, so that the DVRs use the independent format.
Meanwhile, Personal Video Recorders (PVR) have been used for the purposes of recording, reproducing and instant recording broadcast signals, and the PVRs are developed to overcome the technical limitations of conventional Video Cassette Recorders (VCRs). That is, the PVRs solve a problem of the deterioration of the image quality of analog VCR tapes by using HDD devices. The instant recording function, in which the HDD devices are used not as storage devices but as a type of a time delay buffer so that live broadcasts may be instantly paused, is PVRs' advanced feature compared to the conventional VCRs.
When classified by the types of broadcast signals, analog-type PVRs convert analog broadcast signals into digital data, compress the digital data into an independent format and store the compressed digital data on a HDD device, whereas digital-type PVRs, being combined with digital STBs, perform both Set Top Box (STB) functions of decoding digital broadcast signals and outputting the decoded signals to an external TV, and PVR functions of storing digital broadcast signals as they are and performing the above-described recording, reproducing and instant recording functions.
As described above, the DVRs and the PVRs perform different functions in independent fields because their applications are totally different. That is, schools and banks do not need the PVRs, whereas homes are not equipped with the DVRs. However, according to the recent trend of digital convergence, if they are combined together, the creation of added value may be expected. Further, demands for home security systems start to increase, so that the demands for such combined devices may be expected. Furthermore, if the combined devices are combined with Internet technology and more various operational scenarios are provided, their commercial values are expected to be much larger.